Preparation of Pt@Cu Core-Shell Particles Incorporated in Poly-(3,4-ethylenedioxythiophene) for Catalytic Applications

• Published in: Meeting abstracts (Electrochemical Society) Vol. MA2016-02; no. 46; p. 3386
• Main Authors: Peipmann, Ralf, Endrikat, Anna, Bund, Andreas
• Format: Journal Article
• Language: English
• Published: 01.09.2016
• ISSN: 2151-2043; 2151-2035
• DOI: 10.1149/MA2016-02/46/3386

Hybrid materials offer the possibility to combine advantageous properties of the individual components. In the macroscopic world adobe or reinforced concrete are well known examples. The same principle can also be applied to electrodes for electro-catalytic reactions. The usually precious metal catalyst like Pt for fuel cells (or Au for sensors) is reduced in size (and thus in costs) to smaller and smaller particles which are bonded to supporting surfaces. An interesting approach is to prepare a porous matrix in which these catalytic particles can be homogeneously incorporated. Promising candidates are conducting polymers like poly-(3,4-ethylenedioxythiophene) (PEDOT) whose structure can be tuned by the used electrolyte and/or the supporting electrolyte. To homogeneously incorporate the particles they should be prepared in situ with the polymer which is possible by cyclic voltammetry or (reversed) pulse methods. As Pt 2+ has the possibility to oxidize EDOT directly we deposited Cu as an intermediate with the polymer by cyclic voltammetry. In a second step a chemical exchange reaction was performed using a Pt 4+ containing solution. This approach can yield Pt@Cu core shell particles embedded in a polymer matrix. A positive effect of this is also that the electronic structure of the Pt layer is modified by the underlying Cu core which can lead to enhanced catalytic activities. The cyclic voltammograms of the preparation of PEDOT/Cu films show a superposition of PEDOT and Cu features. At potentials more positive than ca. 0.9 V vs. Ag/AgCl sat. KCl polymerization of EDOT occurs while at more negative potentials the capacitive behaviour of the PEDOT film dominates next to the Cu redox waves at ca. 50 mV. SEM/EDX analyses showed that thus prepared films contain 10 to 17 wt% Cu depending on the switch-off potential. If the preparation stopped before Cu oxidation Cu crystallites could be observed on the PEDOT surface and the Cu content was higher. In the case of well oxidized films no distinct Cu centres could be found (see figure 1). The chemical exchange reaction with Pt was monitored by a quartz crystal microbalance (QCM). According to QCM data the deposited mass of Pt corresponds to ca. 60 monolayers on the geometric area. This contribution will discuss the preparation of the PEDOT/Pt@Cu hybrid films as well as the electrochemical and mechanical characterization of these films. This will include CV and impedance (EIS) data as well as QCM data. Fig. 1. SEM images of a PEDOT/Cu film with the preparation stopped at potentials negative to the Cu redox potential. (left) top view of the surface and (right) FIB cross section. Figure 1